From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sridhar Samudrala Subject: Re: [PATCH v11 13/17] Add mp(mediate passthru) device. Date: Tue, 28 Sep 2010 11:48:34 -0700 Message-ID: <4CA23882.1030909@us.ibm.com> References: <1285388855-27410-1-git-send-email-xiaohui.xin@intel.com> <201009281639.59417.arnd@arndb.de> <20100928144311.GB15294@redhat.com> <201009281718.15813.arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: "Michael S. Tsirkin" , Ben Hutchings , xiaohui.xin@intel.com, netdev@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@elte.hu, davem@davemloft.net, herbert@gondor.hengli.com.au, jdike@linux.intel.com To: Arnd Bergmann Return-path: Received: from e39.co.us.ibm.com ([32.97.110.160]:32887 "EHLO e39.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756860Ab0I1Ssp (ORCPT ); Tue, 28 Sep 2010 14:48:45 -0400 In-Reply-To: <201009281718.15813.arnd@arndb.de> Sender: netdev-owner@vger.kernel.org List-ID: On 9/28/2010 8:18 AM, Arnd Bergmann wrote: > On Tuesday 28 September 2010, Michael S. Tsirkin wrote: >> On Tue, Sep 28, 2010 at 04:39:59PM +0200, Arnd Bergmann wrote: >>> Can you be more specific what the problem is? Do you think >>> it breaks when a guest sends VLAN tagged frames or when macvtap >>> is connected to a VLAN interface that adds another tag (or >>> only the combination)? >> I expect the protocol value to be wrong when guest sends vlan tagged >> frames as 802.1q frames have a different format. > Ok, I see. Would that be fixed by using eth_type_trans()? I don't > see any code in there that tries to deal with the VLAN tag, so > do we have the same problem in the tun/tap driver? tun_get_user() does call eth_type_trans(). Not sure why i didn't use it in macvtap code. Need to test it with guest VLAN tagging to make sure it works. > Also, I wonder how we handle the case where both the guest and > the host do VLAN tagging. Does the host transparently override > the guest tag, or does it add a nested tag? More importantly, > what should it do? > I would think If both guest and host do VLAN tagging, the tags will be nested. Thanks Sridhar